IVAS 2022 banner
IVES 9 IVES Conference Series 9 IVAS 9 IVAS 2022 9 The kinetics of grape aromatic precursors hydrolysis at three different temperatures

The kinetics of grape aromatic precursors hydrolysis at three different temperatures

Abstract

In neutral grapes, it is known that most aroma compounds are present as non-volatile precursors. There is strong evidence that supports the existence of a connection between the content of aroma precursors in grapes and the aromatic quality of wine1. Harsh acid hydrolysis is considered the better way to reveal the aroma potential of winemaking grapes, because transformations taking place during fermentation include relevant chemical rearrangements in acid media that are better predicted by acid hydrolysis2. The aim of the present work is to establish a methodology to evaluate the aromatic potential of the grape from the acid hydrolysis in anoxic conditions of its aromatic and phenolic fraction.
In this work, firstly two different samples of Grenache grapes aromatic and phenolic fraction (PAF) were extracted, followed by acid hydrolysis under strict anoxic conditions based on a previously developed methodology3. These PAFs were reconstituted in model wine and aged in duplicate under anoxic conditions at three temperatures: 75, 50 and 35 ºC. The aged model wines were collected at different sampling times 75 ºC (1h, 2h, 6h, 12h, 24h, 48h, 96h), 50 ºC (0.5, 1, 2, 5, 7, 10 and 14 weeks) and at 35ºC (0.5, 1, 5, 3.5, 6, 9 and 12 months).
Hydrolysates were extracted and analyzed by two different analytical methods: esters, free norisoprenoids, terpenoids, phenols, lactones, vanillins and cinnamates were analyzed by SPE-GC-MS4, while varietal thiols were analyzed by LC-QqQ-MS.
The hydrolysates obtained at 50 and 75ºC present sensory profiles congruent with olfactory nuances of unoxidized wine. In fact, the absolute concentration values ​​found for terpenes, lactones and norisoprenoids are within the normal values ​​expected in a wine, except for TDN, which appears in large quantities. However, phenols, derivatives of vanilla and varietal thiols especially 3-mercaptohexanol appear in much higher amounts than would be expected in a Grenache wine, possibly because this type of hydrolysis is capable of release a major part of aromatic potential of grape. Very few differences are observed in the hydrolysis profiles between the two samples. The hydrolysis profile at the same temperature is similar between the samples in most cases even though different amounts of volatiles are obtained. All compounds seem to hydrolyze following two types of behavior that can be explained by the combination of two phenomena: the generation of volatiles (hydrolysis and rearrangements) and the subsequent degradation at wine pH. For those compounds with congruent evolutions at the three different temperatures, a model able to predict the evolution of varietal volatiles at room temperature will be presented.

DOI:

Publication date: June 24, 2022

Issue: IVAS 2022

Type: Poster

Authors

Sánchez Acevedo Elayma1, Lopez Ricardo1 and Ferreira Vicente1

1Laboratory for Aroma Analysis and Enology (LAAE), Universidad de Zaragoza, Instituto Agroalimentario de Aragón (IA2) (UNIZAR-CITA), Zaragoza (Spain)

Contact the author

Keywords

aromatic and phenolic fraction (PAF), acid hydrolisis, aroma

Tags

IVAS 2022 | IVES Conference Series

Citation

Related articles…

Elevational range shifts of mountain vineyards: Recent dynamics in response to a warming climate

Increasing temperatures worldwide are expected to cause a change in spatial distribution of plant species along elevational gradients and there are already observable shifts to higher elevations as a consequence of climate change for many species. Not only naturally growing plants, but also agricultural cultivations are subject to the effects of climate change, as the type of cultivation and the economic viability depends largely on the prevailing climatic conditions. A shift to higher elevations therefore represents a viable adaptation strategy to climate change, as higher elevations are characterized by lower temperatures. This is especially important in the case of viticulture because a certain wine-style can only be achieved under very specific climatic conditions. Although there are several studies investigating climatic suitability within winegrowing regions or longitudinal shifts of winegrowing areas, little is known about how fast vineyards move to higher elevations, which may represent a viable strategy for winegrowers to maintain growing conditions and thus wine-style, despite the effects of climate change. We therefore investigated the change in the spatial distribution of vineyards along an elevational gradient over the past 20 years in the mountainous wine-growing region of Alto Adige (Italy). A dataset containing information about location and planting year of more than 26000 vineyard parcels and 30 varieties was used to perform this analysis. Preliminary results suggest that there has been a shift to higher elevations for vineyards in general (from formerly 700m to currently 850 m a.s.l., with extreme sites reaching 1200 m a.s.l.), but also that this development has not been uniform across different varieties and products (i.e. vitis vinifera vs hybrid varieties and still vssparkling wines). This is important for climate change adaptation as well as for rural development. Mountain areas, especially at mid to high elevations, are often characterized by severe land abandonment which can be avoided to some degree if economically viable and sustainable land management strategies are available.

Modeling the suitability of Pinot Noir in Oregon’s Willamette Valley in a changing climate

Air temperature is the key driver of grapevine phenology and a significant environmental factor impacting yield and quality for a winegrape growing region. In this study the optimal downscaled CMIP5 ensemble for computing thegrowing season average temperature (GST) viticulture climate classification index was determined to spatially compute on a decadal basis predictions of the GST climate index and the grapevine sugar ripeness (GSR) model for Pinot Noir throughout the Willamette Valley (WV) American Viticultural Area (AVA). Forecasts for average temperature and a 220 g/L target sugar concentration level were computed using daily Localized Constructed Analogs (LOCA) downscaled CMIP5 historic and Representative Concentration Pathways (RCP) future climate projections of minimum and maximum daily temperature. We explore spatiotemporal trends of the GST climate classification index and Pinot Noir specific applications of the GSR phenology model for the WV AVA. Spatiotemporal computations of the GST climate index and Pinot Noir specific applications of the GSR model enable the opportunity to explore relationships between their computed values with one intent being to provide updated GST ranges that better align with current temperature-based modeling understanding of Pinot Noir grapevine phenology and the viticultural application of LOCA CMIP5 climate projections for the WV AVA. The Pinot Noir specific applications of the GSR model or the GST index with updated bounds indicate that the percent of the WV AVA area suitable for Pinot Noir production is currently at or near its peak value in the upper 80s to lower 90s of this century.

Legacy of land-cover changes on soil erosion and microbiology in Burgundian vineyards

Soils in vineyards are recognized as complex agrosystems whose characteristics reflect complex interactions between natural factors (lithology, climate, slope, biodiversity) and human activities. To date, most of the unknown lies in an incomplete understanding of soil ecosystems, and specifically in the microbial biodiversity even though soil microbiota is involved in many key functions, such as nutrient cycling and carbon sequestration. Soil biological properties are indicative of soil quality. Therefore, understanding how soil communities are related to soil ecosystem functioning is becoming an essential issue for soil strategy conservation. Here, we propose to assess the importance of land-cover history on the present-day microbiological and physico-chemical properties. The studied area was selected in the Burgundian vineyards (Pernand-Vergelesses, Burgundy, France) where land occupation has been reconstructed over the last 40 years. Soil samples were collected in five areas reflecting various land cover history (forest, vineyards, shifting from forest to vineyards). For each area, physico-chemical parameters (pH, C, N, P, grain size) were measured and DNA was extracted to characterize the abundance and diversity of microbial communities. The obtained results show significant differences in the five areas suggesting that present-day microbial molecular biomass and bacterial taxonomic is partly inherited from past land occupation. Over longer period of time, such study of land-uses legacies may help to better assess ecosystem recovery and the impact of management practices for a better soil quality and vineyards sustainability.

Mesoclimate impact on Tannat in the Atlantic terroir of Uruguay

The study of climate is relevant as an element conditioning the typicity of a product, its quality and sustainability over the years. The grapevine development and growth and the final grape and wine composition are closely related to temperature, while climate components vary at mesoscale according to topography and/or proximity to large bodies of water. The objective of this work is to assess the mesoclimate of the Atlantic region of Uruguay and to determine the effect of topography and the ocean on temperature and consequently on Tannat grapevine behavior.

Modeling island and coastal vineyards potential in the context of climate change

Climate change impacts regional and local climates, which in turn affects the world’s wine regions. In the short term, these modifications rises issues about maintaining quality and style of wine, and in a longer term about the suitability of grape varieties and the sustainability of traditional wine regions. Thus, adaptation to climate change represents a major challenge for viticulture. In this context, island and coastal vineyards could become coveted areas due to their specific climatic conditions. In regions subject to warming, the proximity of the sea can moderate extremes temperatures, which could be an advantage for wine. However, coastal and island areas are particular prized spaces and subject to multiple pressures that make the establishment or extension of viticulture complex.
In this perspective, it seems relevant to assess the potentialities of coastal and island areas for viticulture. This contribution will present a spatial optimization model that tends to characterize most suitable agroclimatic patterns in historical or emerging vineyards according to different scenarios. Thanks to an in-depth bibliography a global inventory of coastal and insular vineyards on a worldwide scale has been realized. Relevant criteria have been identified to describe the specificities of these vineyards. They are used as input data in the optimization process, which will optimize some objectives and spatial aspects. According to a predefined scenario, the objectives are set in three main categories associated with climatic characteristics, vineyards characteristics and management strategies. At the end of this optimization process, a series of maps presents the different spatial configurations that maximize the scenario objectives.